Device for reducing the exhaust smoke of a combustion engine



Dec. 3, 1963 A. MASSARD 3,413,966

DEVICE FOR REDUCING THE EXHAUST SMOKE OF A COMBUSTION ENGINE 'Filed Sept. 28, 1966 United States Patent Office 3,413,966 Patented Dec. 3, 1968 3,413,966 DEVICE FOR REDUCING THE EXHAUST SMOKE OF A COMBUSTION ENGINE Andr Massard, Lyon, France, assignor to Automobiles M. Berliet (Rhone, France), a corporation of France Filed Sept. 28, 1966, Ser. No. 582,707 Claims priority, application France, Oct. 1, 1965, 33,451 1 Claim. (Cl. 123-139) ABSTRACT OF THE DISCLOSURE A device for reducing exhaust smoke from an internal combustion engine during start up or rapid pick up comprising a damping means associated with the fuel regulating device of the enginein such a manner that braking will be exerted on the fuel regulating device between the positions of full load and overload.

to the flow-rate of maintenance (engine idling);

to the flow-rate of full load (engine used on its maximum power curve); and

to the flow-rate of overload cold).

During a rapid transition from the idling position to the full-load position (the case of engine pick-up during a change of gear or when starting-up the vehicle after a period with the engine idling) the rack of the' injection pump, violently projected towards its full-load position, overshoots this position and passes into the zone of overload operation. The engine then receives a flow-rate of fuel greater than the maximum fiow of utilization. This fuel, incompletely burnt, is converted into soot and thus gives a puif of black smoke at the exhaust.

Under these conditions, the invention permits the exhaust smoke to be reduced. To this end, in a combustion engine comprising an injection pump, and onthe said pump a device for regulating the flow of fuel having beyond the regulating position of full load, an overload position especially intended for starting up, the invention is essentially characterized inthat a damping device is associated with the regulating member in order to brake the travel of the latter between the full-load position and the overload position.

One form of construction of a device according to the invention is described below by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view of an injection pump equipped with the device according to the invention;

FIGS. 2 to 4 are detail views illustrating the cooperation of the regulating member of the pump and the damping device associated with this member;

FIG. 5 is a detail view of the braking valve of the damping device.

The injection pump shown partially in FIG. 1 comprises a rack 1 slidably mounted in the pump body 2 and serving (position for starting-up from to regulate, in the usual manner, not shown, the flow of fuel from the pump intended to be injected into the combustion chambers of an engine.

It is known that a rack of this kind is coupled in particular through the intermediary of a rod system and elastic members (not shown), to the accelerator pedal of the engine to be supplied, and it can thus be caused to take-up the three main positions previously defined and shown in FIGS. 2 to 4; the slow-running position (noted by line R, FIG. 2), the full-load position (line C, FIG. 3) and the overload position (line S, FIG. 4).

In accordance with the invention, there is associated with this rac'k a damping device intended to brake its possible travel between the positions C and S and, in the preferred form of embodiment shown in the drawings, this damping device is of the air type. It comprises a cylinder 3 fixed in the axis of the rack on the pump body 2, and a piston 4 which a restoring spring 5 inside the cylinder normally urges into a position of abutment with the rack 2 in the position C of full load (see FIGS. 2 and 3).

The cylinder 3 and the piston 4 form a chamber 6 put into communication with the atmosphere by means of a braking valve 7 mounted in the end of the cylinder. This valve comprises a closure head 8 inside the cylinder and a hollow rod 9 open to the atmosphere and communicating continuously with the interior of the cylinder by a passage 10 intended to brake the flow of the air contained in the cylinder when the piston 4 is displaced by the rack in the travel from C to S.

It results from the foregoing that when starting-up the engine, this damping device does not prevent the rack 2 from being progressively moved to the overload position S by the driver, but the damping device subsequently prevents any rapid or abrupt operation in the same direction, during starting-up or during running, from causing a substantial untimely displacement of the rack beyond its position C towards its position S, this latter position beihg undesirable because of the emission of exhaust smoke which would result.

In addition, this damping device is preferably of the single-acting type, that is to say it acts only in the direction of travel from C to S. To this end, the braking valve 7 is slidably mounted in the end of the cylinder with a certain axial freedom, limited on the one hand by its closure head 8 and on the other by a stop-ring 11 engaged on the rod 9, and the latter is provided with radial passages 12 for the intake of air into the chamber 6, greater than the passage 10.

A rapid return of the piston 4 from the position shown in FIG. 4 to the normal position shown in FIG. 3 can thus be ensured by the spring 5 when the rack 2 is itself brought back, the valve 7 then taking-up the position shown in FIG. 5.

From the point of view of construction, a device of this kind can also be made integral with the pump body and not fixed thereon.

What is claimed is:

1. In an internal combustion engine having an injection pump including means for regulating fuel flow between an idling position through a full load position to an overload position, 'a device for reducing exhaust smoke during starting up and picking up of the engine comprising damping means operatively connected to said fuel regulating means to brake the regulating means during movement from the position of full load to the overload position, said damping means comprising a cylinder, a piston movably mounted in said cylinder and defining a chamber therewith, means in said chamber for biasing said piston towardsengagement with said fuel. regulatingrmeans in the full load position, valve means in said chamber having air outlet means smaller than air-inlet means whereby movement of said piston in response to movement of said fuel regulating means from the full load to overload position will be retarded while recovery will be rapid.

4 References Cited UNITED" STATES PATENTS 2,236,553 4/1941 Voit et al 123-l39.18 3,311,102 3/1967 Voight 123-139 XR LAURENCE M. GOODRIDGE, Primary Examiner. 

